Experimental impacts of grazing on grassland biodiversity and function are explained by aridity

Grazing by domestic herbivores is the most widespread land use on the planet, and also a major global change driver in grasslands. Yet, experimental evidence on the long-term impacts of livestock grazing on biodiversity and function is largely lacking. Here, we report results from a network of 10 experimental sites from paired grazed and ungrazed grasslands across an aridity gradient, including some of the largest remaining native grasslands on the planet. We show that aridity partly explains the responses of biodiversity and multifunctionality to long-term livestock grazing. Grazing greatly reduced biodiversity and multifunctionality in steppes with higher aridity, while had no effects in steppes with relatively lower aridity. Moreover, we found that long-term grazing further changed the capacity of above- and below-ground biodiversity to explain multifunctionality. Thus, while plant diversity was positively correlated with multifunctionality across grasslands with excluded livestock, soil biodiversity was positively correlated with multifunctionality across grazed grasslands. Together, our cross-site experiment reveals that the impacts of long-term grazing on biodiversity and function depend on aridity levels, with the more arid sites experiencing more negative impacts on biodiversity and ecosystem multifunctionality. We also highlight the fundamental importance of conserving soil biodiversity for protecting multifunctionality in widespread grazed grasslands.


Field-specific reporting
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Life sciences
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Ecological, evolutionary & environmental sciences study design
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Study description
Research sample Sampling strategy

Data collection
All Bacterial, fungal and protist sequences have been deposited in NCBI's SRA database under project accession numbers PRJNA995873. All data that support the findings of this study are available in the Figshare database (https://figshare.com/s/a368cc6f2de4f1e0d39d). The mean annual temperature, mean annual precipitation, and aridity level of each site using datafrom the WorldClim global database (https://www.worldclim.org/). Source data are provided with this paper.
This study is based on a standardized field survey includes paired grazing plots (including and excluding livestock) of 10 locations from 3 types of grasslands, where we collected composite topsoil samples and plant samples. The selected sites experienced decades of grazing, and the exclusion of livestock was done over 10 years at each site. Based on this survey, we aim to compare levels of biodiversity and multifunctionality in grazed and ungrazed grasslands, and examine the relationship between biodiversity and multifunctionality.
Samples have been collected from ungrazed and grazed grasslands across 10 experimental sites including three different types of grasslands situated along a 1100 km transect from east to west including meadow steppes, typical steppes and desert steppes across an aridity gradient (from less to more arid). These sites represent three major grassland types including the most dominant vegetation characteristics found in northern China. The samples were selected to cover the entire biogeographic range along with a broad range of environmental gradients.
We choose 10 geographically distinct sites to get the aridity gradients within this region. At each site, a pair of sampling area (50 m × 50 m) was selected randomly on both sides of the fence, and 5 1 m × 1 m plots (5 replicates for control including grazing and 5 replicates for grazing exclusion) were set at the four corners and the center of the area, which has been estimated to be a good compromise between enough space to encompass the variability in plant and soil community based on the literature. Our samples were selected to cover the entire biogeographic range along with a broad range of environmental gradients in northern China (Supplementary Fig. 1 and Table 1) Data collection on site was mainly recorded by GL and MZ, with the help of YW and YX. Above-ground biomass was clipped at the ground level and oven dried at 65°C for 48 h. Then it was weighed and ground into a fine powder on a ball mill for plant community nitrogen and phosphorus analyses. Soil samples were collected by taking five soil cores (2.5-cm diameter) at 10 cm depth in each of the five 1 × 1 m plots at each site. The five soil cores were mixed in situ to form one composite sample representing each plot. After removing the rocks and roots, the soil was passed through a 2-mm-mesh sieve and separated into two parts. One part was air-dried and used to determine soil organic C. The other part was kept in a freezer (MOBICOOL CoolFreeze CF-50) to maintain a temperature of -18°C and carried back to the laboratory as soon as possible for soil microbial community analysis and microbial biomass C, N and available nitrogen analysis. We then collected belowground root biomass to a depth of 30 cm using soil cores (diameter 7 cm) in each of these five quadrats as well. Roots were collected by rinsing the samples using sieves (mesh size 0.25 mm) at the same day, and